Spark emission

Spark emission spectroscopy (OES) is an analytical method used in metallurgy and materials science to determine the chemical composition of metallic materials. This method plays a crucial role in quality control and material testing, because it permits a quick, exact analysis of the alloy elements in numerous metals.

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Spark emission spectroscopy to determine the chemical composition of metallic materials

What is spark emission spectroscopy?

Spark emission spectroscopy (OES, also termed optical emission spectrometry) is a method for the chemical analysis of metallic materials. It is used during material testing to identify individual alloy elements in a sample.

Spark emission spectroscopy at Quality Analysis

Using spark emission spectroscopy (OES), individual alloy elements are analysed qualitatively and quantitatively with the highest accuracy at Quality Analysis. The alloy composition identified is compared with the limits listed in the usual standards, the limits in the steel code, or customer requirements and evaluated. Our informative analysis report confirms whether the material has a specific material quality. In this way quick, dependable statements can be made about the elementary composition of a material and conclusions drawn about its characteristics.


Fast, reliable
measurement results


  • Analysis of alloys made of iron, aluminium, copper, zinc, magnesium, titanium, cobalt and nickel
  • Quantitative and qualitative analysis
  • Comparison with common standards, steel codes or customer requirements
  • Numerous methods for correct sample preparation

How does spark emission spectroscopy work?

Three components are required to undertake an analysis using spark emission spectroscopy. On the one hand, that is an electrical source that vaporises the sample material and in this way excites the atoms resulting in an optical emission. The second component is the spectrometer – the optical system in which the incident light is split into its individual wavelengths by a diffraction grating. It is therefore used to separate the light into its spectral components. This procedure is crucial to be able to identify the different elements in the sample material. A detection system is then used to measure the intensity of the light at each individual wavelength and in this way define the intensity of the specific emission lines. The result is a graphic depiction of the light emission at various wavelengths. This depiction makes it possible to determine the chemical composition of the sample.

What is the procedure during analysis using spark emission spectroscopy?

Spark emission spectroscopy is based, as its name already suggests, on the generation of an electrical spark or arc. This spark or arc heats the sample to be analysed in a pre-specified range. The high-energy spark discharge in an argon atmosphere occurs between a prepared, roughly ground part of the item inspected and a copper or silver electrode. As a result an arc is produced that vaporises the sample material and releases atoms and ions excited by electron impacts. These emissions can be measured: the radiation is guided to optical systems via light conductors that break down the radiation into its individual spectral components. The spectrometer measures the specific lines in the radiation emitted and converts them into a spectrum.

Emission lines for the characterisation of the elements

The emission lines are the feature with which each chemical element can be identified because they represent the different wavelengths of the radiation emitted. These lines are produced when electrons in an atom absorb energy, typically due to an electrical discharge such as a spark or arc. This addition of energy places the electrons in higher energy states located in orbits further away from the core of the atom.
These excited states are energetically unstable. For this reason, after a short time the electrons drop back to lower energy states and, in the process, release energy in the form of light. This light is termed an optical emission. Each chemical element generates unique emission lines with defined wavelengths that correspond to the specific transitions of the electrons between the energy levels. These characteristic lines make it possible to identify the elements in a sample and determine their concentrations.

The wavelength in the spectrum

The individual spectral lines are measured using detectors and the data processed to prepare a continuous line spectrum. This process is undertaken by the spark spectrometer that is able to measure the intensity of the individual wavelengths and thus prepare a detailed spectrum. The spectrum produced forms a unique fingerprint of the elements in the sample. It consists of brighter and darker lines that are indicative of the intensity of the radiation emitted at certain wavelengths. The lines in the spectrum are the result of the transitions of electrons between different energy states in the atoms of the element analysed. Brighter lines correspond to a brighter emission intensity and therefore a higher concentration of the corresponding element.

The analysis and identification of the elements

In this way, in a few seconds all chemical elements can be analysed quantitatively and all elements in the sample identified. The sensitivity and precision of the analysis are further improved by variants such as inductively coupled plasma spark emission spectroscopy (ICP-OES).

The advantages of spark emission spectroscopy

Spark emission spectroscopy permits the quick, efficient, reliable, quantitative and qualitative determination of the composition of a metallic sample. Because neither the preparation of the samples nor the method itself are particularly time-consuming, this method is very suitable for rapid analyses for quality assurance.

Spark emission spectroscopy
precise even in very low concentrations

Along with metals, it is also possible to use OES to verify the presence of lighter elements such as carbon. In addition, compared to other analytical techniques, the presence of nearly all relevant elements and their concentrations in various metals can be verified using spark emission spectroscopy. These include important elements such as carbon, sulphur, phosphorous, boron and nitrogen. The method is also very precise even with very low concentrations and reliably identifies traces of undesirable elements – and comparatively inexpensively. Due to the speed with which it can be implemented and its accuracy, spark emission spectroscopy is also suitable for mass tests.

Spark emission spectroscopy: suitable for numerous samples

Spark emission spectroscopy is used effectively for the analysis of molten metals in primary metal production, such as obtaining metals from ores, as well as in secondary metal production, for instance in metal recycling. Here there are various possible different forms of sample: solid materials, wires and small components. Spectral analysis permits the exact determination of the composition and purity of these materials. It is a prerequisite that the samples are metallic and electrically conductive to be able to generate a spark.

Where is spark emission spectroscopy used?

Spark emission spectroscopy is widely used in various applications; it is particularly proven in quality assurance. Its applications range from damage analysis, metallography and material testing to incoming goods inspection and product development. In quality assurance, this analytical method permits the quick, precise determination of the chemical composition of metals. In addition, spark emission spectroscopy assists with damage analysis by providing detailed insights into the material characteristics.


In medical technology, OES can be used during the analysis of metal alloys in medical implants, instruments or other medical devices. In this way it can be ensured that the materials used meet the necessary quality standards.


Additive manufacturing

Spark emission spectroscopy makes it possible to check the chemical composition of additively manufactured parts so that they have the required material characteristics. This aspect is important to ensure that the parts printed have the required material characteristics.


Electronics manufacturing

It is important to know the chemical composition of the metal alloys used to be able to ensure that electronic components meet the specific requirements for conductivity and durability. During damage analysis on electronic components, OES can contribute to the identification of the causes of defects or structural problems. By means of the analysis of the chemical composition, it is also possible to identify manufacturing defects or irregularities in the material.


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